| 摘要 |
The invention is betaines of squaric acid of the general formula (I) <IMAGE> in which X is either R3Z, where Z is then N, P, As, S or Se and n where Z = N, P and As denotes three and where Z = S and Se denotes two, and the organic radicals R are identical or different and denote an alkyl radical from C1 to C12, a cycloalkyl radical from C5 to C12, an aryl radical from C6 to C15 or an aralkyl radical from C6 to C15 or in which X is a saturated, unsaturated or aromatic heterocycle whose hetero atom from the group consisting of N, P, As, S and Se is the carrier of the positive partial charge and is directly connected to the 2-hydroxy-3,4-dioxocyclobutenyl betaine radical, 1-(2-hydroxy-3,4-dioxocyclobutenyl)triphenylphosphonium betaine being excluded. A process for the preparation of these betaines is additionally described in which a 1,2-disubstituted 3,4-dioxo-1,2-cyclobutene of the general formula (2) is reacted with a compound of the general formula X, if appropriate in the presence of water, of an inert organic solvent and/or acetic anhydride: <IMAGE>
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